Methods and apparatus for scanning an object in a computed tomography system

Abstract

The present invention, in one form, is a system for generating a high resolution image of an object from projection data acquired during a computed tomography scan. The system includes a gantry having an x-ray source which rotates around the object. The x-ray source emits an x-ray beam which is collimated with a collimator having a collimator aperture to define an x-ray beam width, or slice thickness. The projection data is reconstructed to generate image data for adjacent image slices. A deconvolution algorithm is applied to the image data to generate a deconvolved image having a finer, i.e., smaller, resolution than the collimator aperture.

We claim: 
     
       1. A method for generating image data of an object scanned by a computed tomography system, the computed tomography system including a gantry having an x-ray source which rotates around the object, said method comprising the steps of: obtaining projection data for at least two adjacent image slices;   processing the obtained projection data to generate image data; and   deconvolving the image data in a z-direction.   
     
     
       2. A method in accordance with claim 1 wherein obtaining projection data comprises the step of scanning the object with a helical scan. 
     
     
       3. A method in accordance with claim 2 wherein scanning the object comprises the step of performing a helical scan with a 0.5β:α helical pitch, where α is a collimator aperture size and β is a slice thickness. 
     
     
       4. A method in accordance with claim 1 wherein deconvolving the image data comprises using a kernel whose size is at least 2. 
     
     
       5. A method in accordance with claim 1 wherein obtaining projection data comprises the step of scanning the object with an axial scan. 
     
     
       6. A method in accordance with claim 5 wherein the projection data obtained for one of the image slices at least partially overlaps the projection data obtained for another of the image slices. 
     
     
       7. A method in accordance with claim 1 wherein deconvolving the image data comprises the step of modifying a reconstruction kernel to improve x-y resolution. 
     
     
       8. A system for generating image data of an object, said system comprising a gantry having an x-ray source which rotates around the object, said system configured to: obtain projection data for at least two image slices;   process the obtained projection data to generate image data; and   deconvolve the image data in a z-direction.   
     
     
       9. A system in accordance with claim 8 further comprising a kernel whose size is at least 2. 
     
     
       10. A system in accordance with claim 8 wherein to obtain projection data, said system is configured to scan the object with an axial scan. 
     
     
       11. A system in accordance with claim 8 wherein to obtain projection data, said system is configured to scan the object with a helical scan. 
     
     
       12. A system in accordance with claim 11 wherein said system is further configured to perform a helical scan with a 0.5β:α helical pitch, where α is a collimator aperture size and β is a slice thickness. 
     
     
       13. A method for generating data of an object scanned by a computed tomography system, the computed tomography system including a gantry having an x-ray source which rotates around the object, said method comprising the steps of: obtaining projection data for at least two adjacent slices;   deconvolving the projection data in a projection space, and processing the deconvolved projection data to generate image data to produce an image having a slice thickness less than the slice thickness of the projection data adjacent slices.   
     
     
       14. A method in accordance with claim 13 wherein obtaining projection data comprises the step of scanning the object with a helical scan. 
     
     
       15. A method in accordance with claim 13 wherein scanning the object comprises the step of performing a helical scan with a 0.5β:α helical pitch, where α is a collimator aperture size and β is a slice thickness. 
     
     
       16. A method in accordance with claim 13 wherein deconvolving the projection data comprises using a kernel whose size is at least 2. 
     
     
       17. A method in accordance with claim 13 wherein obtaining projection data comprises the step of scanning the object with an axial scan. 
     
     
       18. A system for generating image data of an object, said system comprising a gantry having an x-ray source which rotates around the object, said system configured to: obtain projection data for at least two adjacent slices;   deconvolve the projection data in a projection space; and   process the deconvolved projection data to generate image data to produce an image having a slice thickness less than the slice thickness of the projection data adjacent slices.   
     
     
       19. A system in accordance with claim 18 wherein to obtain projection data, said system is configured to perform an axial scan of the object. 
     
     
       20. A system in accordance with claim 18 wherein to obtain projection data, said system is configured to scan the object with a helical scan.